Aqueous dispersions and coatings comprising modified epoxy resins comprising the reaction product of rosin and a dienophile

ABSTRACT

Aqueous dispersions and coatings comprising modified epoxy resins comprising the reaction product of rosin and a dienophile, further reacted with an epoxy resin, are disclosed.

FIELD OF THE INVENTION

The present invention relates generally to aqueous dispersions andcoatings comprising a modified epoxy resin.

BACKGROUND OF THE INVENTION

The price of raw materials used in many manufacturing processescontinues to rise, particularly those whose price rises or falls withthe price of oil. Because of this, and because of the predicteddepletion of oil reserves, raw materials derived from renewableresources or alternative resources may be desired. An increase in demandfor environmentally friendly products, together with the uncertainty ofthe variable and volatile petrochemical market, has promoted thedevelopment of raw materials from renewable and/or inexpensive sources.

SUMMARY OF THE INVENTION

The present invention is directed to an aqueous dispersion comprising amodified epoxy resin comprising the reaction product of rosin and adienophile comprising a carboxylic group and/or an anhydride group,further reacted with an epoxy resin.

The present invention is further directed to a coating comprising amodified epoxy resin comprising the reaction product of rosin and adienophile comprising a carboxylic group and/or an anhydride group,further reacted with an epoxy resin.

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to an aqueous dispersion comprising amodified epoxy resin comprising the reaction product of rosin and adienophile. This reaction product is further reacted with an epoxyresin, which product is sometimes referred to herein as the “modifiedepoxy”, “modified epoxy resin” or like terms.

It will be understood that rosin actually comprises a mixture ofcompounds, with abietic acid often being predominant (i.e. more abieticacid than any other component). Rosin is commercially available as, forexample, gum rosin, wood rosin, and tall oil rosin. Abietic acid may beused according to the present invention in its natural form or it may bepurified using techniques known to those skilled in the art. In itsnatural form as a rosin or rosin acid, the abietic acid may be presentwith isomeric forms such as levoprimaric and resin acids of the pimarictype. Oleoresin material can also be present, as can dihydroabietic acidand dehydroabietic acid. Since rosin is a complex mixture of mainlytwenty carbon atom fused ring, mono-carboxylic acids and a small amountof nonacidic components, where the resin acid molecule has the doublebonds and the carboxylic acid group, any derivative can be used thatmaintains the carboxylic acid and the diene group. One suitable exampleof rosin that can be used is SYLVAROS NCY, a tall oil rosin availablefrom Arizona Chemical, and another is Brazilian Gum rosin fromGehring-Montgomery.

The rosin is reacted with a dienophile comprising a carboxylic groupand/or anhydride group. Particularly suitable dienophiles includeα,β-ethylenically unsaturated mono or dicarboxylic acids or anhydridessuch as fumaric acid, maleic acid, acrylic acid, methacrylic acid,itaconic acid, citraconic acid and maleic anhydride. Any otherdienophile comprising a carboxylic group and/or an anhydride group canalso be used.

The rosin and the dienophile can be reacted in a Diels Alder reactionunder conditions well known in the art, such as between the meltingpoint of the rosin and the boiling point of the dienophile. The reactioncan be carried out at elevated pressure in order to increase the boilingpoint of the dienophile. The Diels Alder reaction between rosin and adienophile containing a carboxylic group and/or anhydride group orgroups is described, for example, in Polymer from RenewableResources—13, Polymers from Rosin Acrylic Acid Adduct, Roy, Kundu andMaiti, Eur. Polym. J., 26(4), 471, 1990; and in Diels-Alder Polymersfrom Resinic Acids, Mustata and Bicu, Journal of Polymer Engineering,25(3), 217, 2005, both of which are incorporated by reference herein.This reaction will result in the carboxylated Diels Alder adduct of therosin (“rosin adduct”). It will be appreciated that the rosin adductwill have on average more than one carboxylic acid functionality permolecule. In certain embodiments the rosin adduct has two carboxylicacid functionalities, one from the rosin and one from the dienophile.The number of carboxylic acid groups per molecule of rosin adduct can becontrolled by varying the number of carboxylic acid/anhydride groups permolecule of dienophile and/or by varying the ratio of rosin todienophile. Use of a dienophile with one carboxylic acid/anhydride groupper molecule is particularly suitable. The molar ratio of rosin acidgroups to dienophile can be 1:0.25 to 1:2, such as 1:0.5 to 1:1.1, or1:0.8 to 1:1. When the rosin adduct contains more than two carboxylicacid and/or anhydride functionalities, some of the carboxylic acidand/or anhydride functionalities can be removed by modification of therosin adduct with a compound having a functionality reactive withcarboxylic acid/anhydride, for example an epoxy group or a hydroxylgroup. Examples of such modifying compounds include CARDURA E10(glycidyl ester of versatic acid, available from Hexion SpecialtyChemicals), propylene oxide or octanol. The rosin can comprise 95 to 40,such as 90 to 70, wt % of the total solids weight of the rosin adduct.

The rosin adduct is then reacted with the epoxy resin. In certainembodiments, the epoxy resin has at least two epoxy functionalities. Aportion of the epoxy functionality will react with the carboxylic acidand/or anhydride functionality on the rosin adduct, and a portion willremain unreacted.

Suitable epoxy resins include but are not limited to those having a1,2-epoxy equivalency greater than one, such as at least two; that is,polyepoxides that have on average two epoxide groups per molecule. Ingeneral, the epoxide equivalent weight of the polyepoxide can range from100 to 2000, such as from 180 to 1200 or 180 to 500. The epoxy resinsmay be saturated or unsaturated, cyclic or acyclic, aliphatic,alicyclic, aromatic or heterocyclic. It may contain substituents such ashalogen, hydroxyl, and/or ether groups. Particularly suitablepolyepoxides are polyglycidyl ethers of polyhydric alcohols, such ascyclic polyols, such as polyglycidyl ethers of polyhydric phenols suchas Bisphenol A. These polyepoxides can be produced by etherification ofpolyhydric phenols with an epihalohydrin or dihalohydrin such asepichlorohydrin or dichlorohydrin in the presence of alkali. Othercyclic polyols can also be used in preparing the polyglycidyl ethers ofcyclic polyols. Examples of other cyclic polyols include alicyclicpolyols, particularly cycloaliphatic polyols such as 1,2-cyclohexanedioland 1,2-bis(hydroxymethyl)cyclohexane. Epoxy group-containing acrylicpolymers can also be used. These polymers typically have an epoxyequivalent weight ranging from about 750 to 2000. Because a portion ofthe epoxy functionality remains unreacted, the modified epoxy resin isepoxy functional. “Epoxy functional”, and like terms, as used hereinrefer to a compound or polymer having at least one unreacted epoxygroup. This epoxy group can undergo reaction with, for example, acarboxylic acid to form an ester bond, with a primary amine to form asecondary amine or with a secondary amine to form a tertiary amine. Inthis manner, the modified epoxy resin used according to the presentinvention can be crosslinked or can otherwise form at least a portion ofa coating.

The modified epoxy resin can be prepared by any means known in the art,such as the methods that follow: the epoxy resin and rosin adduct arereacted together neat or in the presence of an inert organic solvent;any suitable solvent can be used such as a ketone, including methylisobutyl ketone and/or methyl amyl ketone, aromatics such as tolueneand/or xylene, and/or glycol ethers such as the dimethyl ether ofdiethylene glycol. The reaction is typically conducted at a temperatureof 80° C. to 160° C. for 30 to 180 minutes until an epoxygroup-containing resinous reaction product is obtained. Alternativelythe reaction can be carried out in a continuous reactor and can beconducted at a temperature of 140° C. to 280° C. for 1 to 20 minutes.The equivalent ratio of reactants, i.e., epoxy groups:carboxylicacid/anhydride groups, is typically from about 1.00:0.20 to about 1.00:0.80.

It will be appreciated that the reaction between the rosin adduct andthe epoxy resin may actually yield a mixture of reaction productsincluding molecules containing rosin adduct, epoxy resin and two epoxygroups, molecules containing rosin adduct, epoxy resin and one epoxygroup, unreacted epoxy resin, and/or unreacted rosin adduct. Use of anexcess of epoxy resin in the reaction will minimize if not eliminate thepresence of unreacted rosin adduct in the reaction mixture. Theconditions can be controlled to result in a reaction mixture that ispredominantly molecules containing rosin adduct, epoxy resin and twoepoxy groups.

As noted above, the present invention is directed to an aqueousdispersion comprising the modified epoxy described above. Dispersionscan be prepared by converting unreacted epoxy groups in the modifiedepoxy resin to cationic or anionic groups. In certain embodiments theunreacted epoxy groups are converted to cationic salt groups. Cationicsalt groups can be introduced by the reaction of epoxy functionality onthe modified epoxy resin with appropriate salt forming compounds. Forexample, sulfonium salt groups can be introduced by reacting a sulfidein the presence of an acid, as described in U.S. Pat. Nos. 3,959,106 and4,715,898 hereby incorporated by reference; amine salt groups can bederived from the reaction of epoxy functionality on the modified epoxyresin with a compound containing a primary or secondary amine group,such as methylamine, diethanolamine, ammonia, diisopropanolamine,N-methyl ethanolamine, diethylentriamine, dipropylenetriamine,bishexamethylenetriamine, the diketimine of diethylentriamine, thediketimine of dipropylenetriamine, the diketimine ofbishexamethylenetriamine and mixtures thereof. The amine groups can thenbe at least partially neutralized with an acid. Suitable acids includeorganic and inorganic acids such as formic acid, acetic acid, lacticacid, phosphoric acid, dimethylolpropionic acid, sulfamic acid andmixtures thereof. The resulting modified epoxy resin can containprimary, secondary and/or tertiary amino groups.

The modified epoxy resin comprising cationic or anionic groups can bedispersed in a dispersing medium, such as water. The dispersion step maybe accomplished by combining the neutralized or partially neutralizedmodified epoxy resin with the dispersing medium. Neutralization anddispersion can be accomplished in one step by combining the resin andthe dispersing medium, or by any other means known in the art. Themodified epoxy resin can be added to the dispersing medium or thedispersing medium can added to the resin (or its salt). In certainembodiments, the pH of the dispersion is within the range of 4 to 9. Themodified epoxy can comprise 5 to 60 wt %, such as 10 to 50 wt % of theaqueous dispersion, with weight percent based on total weight of thedispersion.

The present invention is further directed to a coating comprising amodified epoxy as described herein, such as in the form of the aqueousdispersion also described herein. A “coating” according to the presentinvention will generally be understood as a composition that, whencured, can form a substantially continuous film or layer that mayprovide a decorative and/or protective function and in certainembodiments is not tacky or sticky. The coatings of the presentinvention can comprise 5 to 100 wt %, such as 10 to 95 or 20 to 90 wt %,based on total solids weight, of the modified epoxy resin. When theseresins are used in a coating, the coating may comprise 10 wt % orgreater rosin, such as 20 wt % or greater, or 30 wt % or greater, withweight percent based on total solids weight.

It will be appreciated that when the present modified epoxy resins areused in a coating according to the present invention, they can form allor part of the film-forming resin of the coating. In certainembodiments, one or more additional film-forming resins are also used inthe coating. For example, the coating compositions can comprise any of avariety of thermoplastic and/or thermosetting compositions known in theart. The coating compositions may be water-based or solvent-based liquidcompositions, or, alternatively, may be in solid particulate form, i.e.,a powder coating.

Thermosetting or curable coating compositions typically comprise filmforming polymers or resins having functional groups that are reactivewith either themselves or a crosslinking agent. The film-forming resincan be selected from, for example, epoxy resins, acrylic polymers,polyester polymers, polyurethane polymers, polyamide polymers, polyetherpolymers, polysiloxane polymers, copolymers thereof, and mixturesthereof. Generally these polymers can be any polymers of these typesmade by any method known to those skilled in the art. Such polymers maybe solvent borne or water dispersible, emulsifiable, or of limited watersolubility. The functional groups on the film-forming resin may beselected from any of a variety of reactive functional groups including,for example, carboxylic acid groups, amine groups, epoxide groups,hydroxyl groups, thiol groups, carbamate groups, amide groups, ureagroups, isocyanate groups (including blocked isocyanate groups)mercaptan groups, and combinations thereof. In certain embodiments, theuse of hydroxy free drying and/or semi drying fatty acid esters and/oroil esters is specifically excluded.

Appropriate mixtures of film-forming resins may also be used in thepreparation of the coating compositions.

The thermosetting coating compositions typically comprise a crosslinkingagent that may be selected from, for example, aminoplasts,polyisocyanates including blocked isocyanates, polyepoxides,beta-hydroxyalkylamides, polyacids, anhydrides, organometallicacid-functional materials, polyamines, polyamides, and mixtures of anyof the foregoing. In certain embodiments, the modified epoxy resin canbe self crosslinking. Self crosslinking means that the reaction productcontains functional groups that are capable of reacting with themselves,such as alkoxysilane groups, or that the reaction product containsfunctional groups that are coreactive, for example hydroxyl groups andblocked isocyanate groups. In certain embodiments, blocked isocyanategroups can be introduced into the modified epoxy resin by reactingresidual epoxy groups with the reaction product of a polyaminecontaining primary and secondary amine groups and an acyclic carbonateas described in WO 2006110515, incorporated by reference herein.

In certain embodiments, the present coating is not a cationicelectrodepositable coating (“ecoat”). A cationic ecoat will beunderstood as one in which cationic salt groups are introduced by thereaction of the epoxy group with appropriate salt forming compounds

The coating compositions may also include a solvent. Suitable solventsinclude water, organic solvent(s) and/or mixtures thereof. Suitablesolvents include glycols, glycol ether alcohols, alcohols, ketones, andaromatics, such as xylene and toluene, acetates, mineral spirits,naphthas and/or mixtures thereof. “Acetates” include the glycol etheracetates. In certain embodiments, the solvent is a non-aqueous solvent.“Non-aqueous solvent” and like terms means that less than 50 percent ofthe solvent is water. For example, less than 10 percent, or even lessthan 5 percent of the solvent can be water. It will be understood thatmixtures of solvents, including or excluding water in an amount of lessthan 50 percent, can constitute a “non-aqueous solvent”. In otherembodiments, the coating is aqueous or water-based. This means that 50%or more of the solvent is water. These embodiments have less than 50%,such as less than 20%, less than 10%, less than 5% or less than 2%solvent.

If desired, the coating compositions can comprise other optionalmaterials well known in the art of formulating coatings, such asplasticizers, anti-oxidants, hindered amine light stabilizers, UV lightabsorbers and stabilizers, surfactants, flow control agents, thixotropicagents, colorants, fillers, organic cosolvents, reactive diluents,catalysts, grind vehicles, and other customary auxiliaries.

As used herein, the term “colorant” means any substance that impartscolor and/or other opacity and/or other visual effect to thecomposition. The colorant can be added to the coating in any suitableform, such as discrete particles, dispersions, solutions and/or flakes.A single colorant or a mixture of two or more colorants can be used inthe coatings of the present invention.

Example colorants include pigments, dyes and tints, such as those usedin the paint industry and/or listed in the Dry Color ManufacturersAssociation (DCMA), as well as special effect compositions. A colorantmay include, for example, a finely divided solid powder that isinsoluble but wettable under the conditions of use. A colorant can beorganic or inorganic and can be agglomerated or non-agglomerated.Colorants can be incorporated into the coatings by grinding or simplemixing. Colorants can be incorporated by grinding into the coating byuse of a grind vehicle, such as an acrylic grind vehicle, the use ofwhich will be familiar to one skilled in the art.

Example pigments and/or pigment compositions include, but are notlimited to, carbazole dioxazine crude pigment, azo, monoazo, disazo,naphthol AS, salt type (lakes), benzimidazolone, condensation, metalcomplex, isoindolinone, isoindoline and polycyclic phthalocyanine,quinacridone, perylene, perinone, diketopyrrolo pyrrole, thioindigo,anthraquinone, indanthrone, anthrapyrimidine, flavanthrone, pyranthrone,anthanthrone, dioxazine, triarylcarbonium, quinophthalone pigments,diketo pyrrolo pyrrole red (“DPPBO red”), titanium dioxide, carbonblack, carbon fiber, graphite, other conductive pigments and/or fillersand mixtures thereof. The terms “pigment” and “colored filler” can beused interchangeably.

Example dyes include, but are not limited to, those that are solventand/or aqueous based such as acid dyes, azoic dyes, basic dyes, directdyes, disperse dyes, reactive dyes, solvent dyes, sulfur dyes, mordantdyes, for example, bismuth vanadate, anthraquinone, perylene, aluminum,quinacridone, thiazole, thiazine, azo, indigoid, nitro, nitroso,oxazine, phthalocyanine, quinoline, stilbene, and triphenyl methane.

Example tints include, but are not limited to, pigments dispersed inwater-based or water miscible carriers such as AQUA-CHEM 896commercially available from Degussa, Inc., CHARISMA COLORANTS andMAXITONER INDUSTRIAL COLORANTS commercially available from AccurateDispersions division of Eastman Chemical, Inc.

As noted above, the colorant can be in the form of a dispersionincluding, but not limited to, a nanoparticle dispersion. Nanoparticledispersions can include one or more highly dispersed nanoparticlecolorants and/or colorant particles that produce a desired visible colorand/or opacity and/or visual effect. Nanoparticle dispersions caninclude colorants such as pigments or dyes having a particle size ofless than 150 nm, such as less than 70 nm, or less than 30 nm.Nanoparticles can be produced by milling stock organic or inorganicpigments with grinding media having a particle size of less than 0.5 mm.Example nanoparticle dispersions and methods for making them areidentified in U.S. Pat. No. 6,875,800 B2, which is incorporated hereinby reference. Nanoparticle dispersions can also be produced bycrystallization, precipitation, gas phase condensation, and chemicalattrition (i.e., partial dissolution). In order to minimizere-agglomeration of nanoparticles within the coating, a dispersion ofresin-coated nanoparticles can be used. As used herein, a “dispersion ofresin-coated nanoparticles” refers to a continuous phase in which isdispersed discreet “composite microparticles” that comprise ananoparticle and a resin coating on the nanoparticle. Exampledispersions of resin-coated nanoparticles and methods for making themare identified in U.S. application Ser. No. 10/876,031 filed Jun. 24,2004, which is incorporated herein by reference, and U.S. ProvisionalApplication No. 60/482,167 filed Jun. 24, 2003, which is alsoincorporated herein by reference.

Example special effect compositions that may be used in the coating ofthe present invention include pigments and/or compositions that produceone or more appearance effects such as reflectance, pearlescence,metallic sheen, phosphorescence, fluorescence, photochromism,photosensitivity, thermochromism, goniochromism and/or color-change.Additional special effect compositions can provide other perceptibleproperties, such as reflectivity, opacity or texture. In a non-limitingembodiment, special effect compositions can produce a color shift, suchthat the color of the coating changes when the coating is viewed atdifferent angles. Example color effect compositions are identified inU.S. Pat. No. 6,894,086, incorporated herein by reference. Additionalcolor effect compositions can include transparent coated mica and/orsynthetic mica, coated silica, coated alumina, a transparent liquidcrystal pigment, a liquid crystal coating, and/or any compositionwherein interference results from a refractive index differential withinthe material and not because of the refractive index differentialbetween the surface of the material and the air.

In certain non-limiting embodiments, a photosensitive composition and/orphotochromic composition, which reversibly alters its color when exposedto one or more light sources, can be used in the coating of the presentinvention. Photochromic and/or photosensitive compositions can beactivated by exposure to radiation of a specified wavelength. When thecomposition becomes excited, the molecular structure is changed and thealtered structure exhibits a new color that is different from theoriginal color of the composition. When the exposure to radiation isremoved, the photochromic and/or photosensitive composition can returnto a state of rest, in which the original color of the compositionreturns. In one non-limiting embodiment, the photochromic and/orphotosensitive composition can be colorless in a non-excited state andexhibit a color in an excited state. Full color-change can appear withinmilliseconds to several minutes, such as from 20 seconds to 60 seconds.Example photochromic and/or photosensitive compositions includephotochromic dyes.

In a non-limiting embodiment, the photosensitive composition and/orphotochromic composition can be associated with and/or at leastpartially bound to, such as by covalent bonding, a polymer and/orpolymeric materials of a polymerizable component. In contrast to somecoatings in which the photosensitive composition may migrate out of thecoating and crystallize into the substrate, the photosensitivecomposition and/or photochromic composition associated with and/or atleast partially bound to a polymer and/or polymerizable component inaccordance with a non-limiting embodiment of the present invention, haveminimal migration out of the coating. Example photosensitivecompositions and/or photochromic compositions and methods for makingthem are identified in U.S. application Ser. No. 10/892,919 filed Jul.16, 2004 and incorporated herein by reference.

In general, the colorant can be present in the coating composition inany amount sufficient to impart the desired property, visual and/orcolor effect. The colorant may comprise from 1 to 65 wt % of the presentcompositions, such as from 3 to 40 wt % or 5 to 35 wt %, with weightpercent based on the total weight of the composition.

It will be further appreciated that the coatings described herein can beeither “one component” (“1K”), “two component” (“2K”), or evenmulti-component compositions. A 1K composition will be understood asreferring to a composition wherein all of the coating components aremaintained in the same container after manufacture, during storage, etc.A 1K coating can be applied to a substrate and cured by any conventionalmeans, such as by heating, forced air, and the like. The presentcoatings can also be 2K coatings or multi-component coatings, which willbe understood as coatings in which various components are maintainedseparately until just prior to application.

As stated above, in certain embodiments, the modified epoxy of thepresent invention can react with, and become part of the film-formingresin of the coating. That is, the modified epoxy resin described hereinwill react, thereby contributing to the cure of the coating.

The present coatings can be applied to any substrates known in the art,for example automotive substrates and industrial substrates. Thesesubstrates can be, for example, metallic, polymeric, transparent plasticsubstrates, polycarbonate, wood substrates and the like.

The coatings of the present invention can be applied by any meansstandard in the art such as electrocoating, spraying, electrostaticspraying, dipping, rolling brushing, and the like.

The coatings can be applied to a dry film thickness of 0.1 to 5.0 mils,such as 0.5 to 3.0 or 0.9 to 2.0 mils. The coatings of the presentinvention can be used alone, or in combination with other coatings. Forexample, the coatings can be pigmented or unpigmented, and can be usedas a primer, e-coat, base coat, top coat, automotive repair coat and thelike. For substrates coated with multiple coatings, one or more of thosecoatings can be coatings as described herein.

As used herein, unless otherwise expressly specified, all numbers suchas those expressing values, ranges, amounts or percentages may be readas if prefaced by the word “about”, even if the term does not expresslyappear. Also, any numerical range recited herein is intended to includeall subranges subsumed therein. Singular encompasses plural and viceversa. For example, although reference is made herein, including theclaims, to “a” rosin, “a” dienophile, “a” carboxylic acid group, “an”anhydride group, “an” epoxy resin, “a” modified epoxy and the like, oneor more of each of these and any other components can be used.“Including” means “including, but not limited to”. As used herein, theterm “polymer” refers to oligomers and both homopolymers and copolymers,and the prefix “poly” refers to two or more.

EXAMPLES

The following examples are intended to illustrate the invention, andshould not be construed as limiting the invention in any way.

Example 1

Mass (/g) A gum rosin¹ 496.25 B acrylic acid 102.72 C 4-methoxyphenol1.03 ¹Brazillian gum rosin, available from Gehring-Montgomery.

Components A, B and C were charged to a flask equipped with an airinlet, stirrer, condenser and thermocouple. The flask contents wereheated slowly until they reached 140° C. and then this temperature wasmaintained for one hour. The temperature was then increased to 170° C.and then maintained for three hours. The reaction mixture was thenpoured on to a foil lined tray and allowed to cool before being brokenup in to small pieces. The product had an acid value of 222.5 mg KOH/g.

Example 2

Mass (/g) A SYLVAROS NCY² 165.1 B acrylic acid 34.55 C hydroquinone 0.55²Tall oil rosin, available from Arizona Chemical.

Components A, B and C were charged to a flask equipped with an airinlet, stirrer, condenser and thermocouple. The flask contents wereheated slowly until they reached 140° C. and then this temperature wasmaintained for one hour. The temperature was then increased to 170° C.and then maintained for three hours. The reaction mixture was thenpoured on to a foil lined tray and allowed to cool before being brokenup in to small pieces. The product had an acid value of 225.1 mg KOH/g.

Example 3

Mass (/g) A gum rosin 518.67 B acrylic acid 80.52 C 4-methoxyphenol 0.80

Components A, B and C were charged to a flask equipped with an airinlet, stirrer, condenser and thermocouple. The flask contents wereheated slowly until they reached 140° C. and then this temperature wasmaintained for one hour. The temperature was then increased to 170° C.and then maintained for three hours. The reaction mixture was thenpoured on to a foil lined tray and allowed to cool before being brokenup in to small pieces. The product had an acid value of 213.2 mg KOH/g.

Example 4

Mass (/g) A gum rosin 496.25 B acrylic acid 102.72 C 4-methoxyphenol1.03

Components A, B and C were charged to a 1-liter stirred stainless steelpressure reactor. The agitation on the reactor was set at 500 rpms andthe reactor temperature was adjusted to 140° C. The temperature was thenincreased to 200° C. and the pressure was adjusted to 1000 PSI withnitrogen. These conditions were maintained for one hour. The reactor wasthen cooled to 120° C. and vented and the reaction mixture was poured onto a foil-lined tray and allowed to cool before being broken up in tosmall pieces. The product had an acid value of 231.7 mg KOH/g.

Example 5

Mass (/g) 1 EPON 828³ 244.21 2 rosin adduct of Example 1 202.38 3ethyltriphenyl phosphonium 0.30 iodide 4 methyl isobutyl ketone 26.01 5methyl isobutyl ketone 0.73 6 crosslinker, prepared as 194.84 describedbelow 7 DETA diketimine 15.22 8 N-methyl ethanolamine 3.05 ³Glycidylether of Bisphenol A, available from Resolution. ⁴Diketimine formed fromdiethylene triamine and methylisobutyl ketone (72.69% solids inmethylisobutyl ketone).

Components 1-4 were charged to a flask equipped with a nitrogen inlet,stirrer, condenser and thermocouple. The flask contents were heatedslowly until they reached 140° C. and then this temperature wasmaintained for one hour. 5 was added and the temperature was adjusted to127° C. 6 and 7 were added, followed one minute later by 8. After theexotherm, the temperature was adjusted to 116° C. and this temperaturewas maintained for two hours. The modified epoxy resin mixture (618.1 g)was dispersed in aqueous medium by adding it to a mixture of 25.54 g ofsulfamic acid and 337.74 g of deionized water warmed to 30° C. undervigorous agitation. After 30 minutes, 5.32 g of a 30% solution of gumrosin in butylcarbitol formal was added followed, 45 minutes later by493.33 g of deionized water. The dispersion was thinned with moredeionized water and vacuum stripped to remove organic solvent to give adispersion having a solids content of 27.8 percent. The reaction producthad Z average molecular weight of 156 783 (determined by gel permeationchromatography in DMF using polystyrene as a standard).

Example 6

Mass (/g) 1 EPON 828 219.81 2 rosin adduct from Example 2 183.80 3ethyltriphenyl phosphonium 0.28 iodide 4 methyl isobutyl ketone 23.51 5methyl isobutyl ketone 0.66 6 crosslinker 176.08 7 DETA diketimine 13.768 N-methyl ethanolamine 2.76

Components 1-4 were charged to a flask equipped with a nitrogen inlet,stirrer, condenser and thermocouple. The flask contents were heatedslowly until they reached 140° C. and then this temperature wasmaintained for one hour. 5 was added and the temperature was adjusted to127° C. 6 and 7 were added, followed one minute later by 8. After theexotherm, the temperature was adjusted to 116° C. and this temperaturewas maintained for two hours. The modified epoxy resin mixture (558.6 g)was dispersed in aqueous medium by adding it to a mixture of 23.08 g ofsulfamic acid and 305.23 g of deionized water warmed to 30° C. undervigorous agitation. After 30 minutes, 4.80 g of a 30% solution of gumrosin in butylcarbitol formal was added followed, 45 minutes later by445.85 g of deionized water. The dispersion was thinned with moredeionized water and vacuum stripped to remove organic solvent to give adispersion having a solids content of 31.0 percent. The reaction producthad Z average molecular weight of 48 876 (determined by gel permeationchromatography in DMF using polystyrene as a standard).

Example 7

Mass (/g) 1 EPON 828 238.50 2 rosin adduct from Example 3 208.10 3ethyltriphenyl phosphonium 0.30 iodide 4 methyl isobutyl ketone 26.01 5methyl isobutyl ketone 0.73 6 crosslinker 194.84 7 DETA diketimine 15.228 N-methyl ethanolamine 3.05

Components 1-4 were charged to a flask equipped with a nitrogen inlet,stirrer, condenser and thermocouple. The flask contents were heatedslowly until they reached 140° C. and then this temperature wasmaintained for one hour. 5 was added and the temperature was adjusted to127° C. 6 and 7 were added, followed one minute later by 8. After theexotherm, the temperature was adjusted to 116° C. and this temperaturewas maintained for two hours. The modified epoxy resin mixture (618.07g) was dispersed in aqueous medium by adding it to a mixture of 25.54 gof sulfamic acid and 337.74 g of deionized water warmed to 30° C. undervigorous agitation. After 30 minutes, 5.32 g of a 30% solution of gumrosin in butylcarbitol formal was added followed, 45 minutes later by493.33 g of deionized water. The dispersion was thinned with moredeionized water and vacuum stripped to remove organic solvent to give adispersion having a solids content of 35.5 percent. The reaction producthad Z average molecular weight of 33 896 (determined by gel permeationchromatography in DMF using polystyrene as a standard).

Example 8

Mass (/g) 1 EPON 828 245.76 2 rosin adduct of Example 4 200.84 3ethyltriphenyl phosphonium 0.30 iodide 4 methyl isobutyl ketone 26.01 5methyl isobutyl ketone 0.73 6 crosslinker 194.84 7 DETA diketimine 15.228 N-methyl ethanolamine 3.05

Components 1-4 were charged to a flask equipped with a nitrogen inlet,stirrer, condenser and thermocouple. The flask contents were heatedslowly until they reached 140° C. and then this temperature wasmaintained for one hour. 5 was added and the temperature was adjusted to127° C. 6 and 7 were added, followed one minute later by 8. After theexotherm, the temperature was adjusted to 116° C. and this temperaturewas maintained for two hours. The modified epoxy resin mixture (618.07g) was dispersed in aqueous medium by adding it to a mixture of 25.54 gof sulfamic acid and 337.74 g of deionized water warmed to 30° C. undervigorous agitation. After 30 minutes, 5.32 g of a 30% solution of gumrosin in butylcarbitol formal was added followed, 45 minutes later by493.33 g of deionized water. The dispersion was thinned with moredeionized water and vacuum stripped to remove organic solvent to give adispersion having a solids content of 32.0 percent. The reaction producthad Z average molecular weight of 47 612 (determined by gel permeationchromatography in DMF using polystyrene as a standard).

The crosslinker was prepared from the following ingredients:

INGREDIENTS PARTS BY WEIGHT Bis (hexamethylene) triamine⁵ 1938.51Propylene carbonate 1840.68 Methyl isobutyl ketone 1619.65 ⁵DYTEKBHMT-HP available from Invista.

The bis (hexamethylene) triamine was charged to a reaction vessel andheated under a nitrogen atmosphere. The propylene carbonate was addedover 3 hours. The reaction mixture exothermed to 68° C. and was thencooled and maintained at 60° C. The mixture was held at 60° C. for anadditional 2 hours and then methyl isobutyl ketone was added.

Example 9

This example describes the preparation of an electrodeposition bathcomposition. The electrodeposition bath was prepared from a mixture ofthe following ingredients:

INGREDIENTS PARTS BY WEIGHT Resin and deionized water See table belowPlasticizer⁶ 7.3 Flexibilizer⁷ 96.7 Flow Additive⁸ 74.8 ethylene glycol12.0 monohexylether. propylene glycol monomethyl 5.7 ether pigment pasteprepared as 140.8 described below ⁶MAZON-1651, a plasticizer based onbutyl carbitol and formaldehyde, available from BASF. ⁷An aqueousdispersion of a flexibilizer/flow control agent generally in accordancewith U.S. Pat. No. 4,423,166. The flexibilizer/flow control agent wasprepared from a polyepoxide (EPON 828) and a polyoxyalkylenepolyamine(JEFFAMINE D2000 from Texaco Chemical Co.). The flexibilizer/flowcontrol agent was dispersed in aqueous medium with the aid of lacticacid and the dispersion had a resin solids content of 46.2 percent byweight. ⁸A cationic microgel prepared as generally described in ExamplesA and B of U.S. Pat. No. 5,096,556, with the exception that acetic acidinstead of lactic acid was used to disperse the soap of Example A, andEPON 828 solution was added after stripping rather than before inExample B. The resin had a final solids content of 17.9%.

De-ionized Cationic Dispersion Parts Water Parts by Dispersion by WeightWeight Example 7 987.5 1087.1 Example 8 1094.6 968.0

The paint was made by adding the plasticizer, flexibilizer, flowadditive, and solvents to the cationic dispersion under agitation. Theblend was then reduced with 500 parts of the deionized water. Thepigment paste is reduced with 300 parts of the deionized water, and thenblended into the reduced resin mixture under agitation. The remainder ofthe deionized water was then added under agitation. Final bath solidswere about 20%, with a pigment to resin ratio of 0.12:1.0. The paint wasallowed to agitate at least two hours. Thirty percent of the total paintweight was removed by ultrafiltration and replaced with deionized water.

The pigment paste used above was prepared from a mixture of thefollowing ingredients:

INGREDIENTS PARTS BY WEIGHT Cationic grind resin⁹ 525.3 SURFYNOL GA¹⁰1.4 catalyst paste, prepared 175.3 as described below ASP-200¹¹ 316.6CSX-333¹² 4.3 TRONOX CR800E¹³ 40.3 Deionized water 50.3 ⁹As described inExample 2 of U.S. Pat. No. 4,715,898. ¹⁰Nonionic surfactant, availablefrom Air Products and Chemicals, Inc. ¹¹Aluminum silicate, availablefrom Engelhard Corporation. ¹²Carbon black beads, available from CabotCorp. ¹³Titanium dioxide pigment, available from Tronox Inc.

The above ingredients were added sequentially under high shearagitation. After the ingredients were thoroughly blended, the pigmentpaste was transferred to a vertical sand mill and ground to a Hegmanvalue of about 7.25. The pigment paste was then collected. The measuredsolids were 55% following 1 hr @110° C.

The catalyst paste was prepared from a mixture of the followingingredients:

INGREDIENTS PARTS BY WEIGHT Cationic grind resin¹⁴ 527.7n-Butoxypropanol 6.9 FASCAT 4201¹⁵ 312.0 Deionized water 59.8 ¹⁴Asdescribed in Example 2 of U.S. Pat. No. 4,715,898, plus 2% by weight onsolids of ICOMEEN T-2, available from BASF. ¹⁵Available from Arkema,Inc.

The catalyst paste was prepared by sequentially adding the aboveingredients under high shear agitation. After the ingredients werethoroughly blended, the pigment paste was transferred to a vertical sandmill and ground to a Hegman value of about 7.25. The catalyst paste wasthen collected. The measured solids were 51% following 1 hr @110° C.

Electrocoating Procedure:

Bath compositions prepared as described above were electrodeposited ontophosphated cold rolled steel panels, commercially available from ACTLaboratories. The phosphate, which is commercially available from PPGIndustries, Inc., was CHEMFOS 700 with a deionized water rinse.Conditions for cationic electrodeposition were 2 minutes at 92° F.,voltages are listed in the chart below, specific to each resin to yielda cured dry film thickness of about 0.80 mils. The electrocoatedsubstrates were cured in an electric oven for 25 minutes at 350° F. Theelectrocoated panels were tested against a standard electrocoat productand the results are recorded in Table 1. The control product is ED-6280electrocoat available from PPG Industries Inc.

TABLE 1 Test Paint Test Paint based on based on dispersion of dispersionof ED6280 Example 7 Example 8 Control Paint Applied Voltage 150 200 175Scribe creep - 20 4.0 mm 3.5 mm 3.25 mm cycles Corrosion Testing¹⁶Solvent Very slight Very slight No effect Resistance¹⁷ mar mar QCThumidity  10  10  10 adhesion¹⁸ ¹⁶Each coated panel was scribed, cuttingthrough the coating to the metal substrate in an X pattern. The testpanels were then subjected to cyclic corrosion testing by rotating testpanels through a salt solution, room temperature dry, and humidity andlow temperature in accordance with General Motors test method, GM TM54-26. Scribe creep is reported as the maximum width (in millimeters) ofcorrosion across the scribe mark. ¹⁷A cloth soaked in acetone was rubbedback and forth across the panel for a period of 100 double strokes. Theamount of surface damage that has occurred was then rated. ¹⁸Crosshatchadhesion performed before and after condensing humidity exposure for 16hours at 140° F. on a QCT condensation tester (Q-Panel Company,Cleveland, OH). A rating of 10 indicates no adhesion failure.

The above results demonstrate that the compositions of the inventionderived in part from a low cost renewable resource have propertiessimilar to a standard market acceptable electrocoat.

Whereas particular embodiments of this invention have been describedabove for purposes of illustration, it will be evident to those skilledin the art that numerous variations of the details of the presentinvention may be made without departing from the invention as defined inthe appended claims.

1. An aqueous dispersion comprising a modified epoxy resin comprisingthe reaction product of rosin and a dienophile comprising a carboxylicgroup and/or an anhydride group, further reacted with an epoxy resin. 2.The aqueous dispersion of claim 1, wherein the rosin comprisespredominantly abietic acid.
 3. The aqueous dispersion of claim 1,wherein the dienophile comprises acrylic acid.
 4. The aqueous dispersionof claim 1, wherein the dienophile comprises monocarboxylic acid.
 5. Theaqueous dispersion of claim 1, wherein the epoxy resin comprises anepoxy functional acrylic resin.
 6. The aqueous dispersion of claim 1,wherein the epoxy resin comprises the diglycidal ether of bisphenol A.7. The aqueous dispersion of claim 1, wherein the modified epoxy resincomprises 20 to 100 wt % of the dispersion, based on the total weight ofthe dispersion.
 8. The aqueous dispersion of claim 1, wherein themodified epoxy resin comprises 5 to 60 wt % of the dispersion, based onthe total weight of the dispersion.
 9. A coating comprising a modifiedepoxy resin comprising the reaction product of rosin and a dienophilecomprising a carboxylic group and/or an anhydride group, further reactedwith an epoxy resin wherein the coating is not a cationic ecoat.
 10. Thecoating of claim 9, wherein the resin is part of the film-forming resin.11. The coating of claim 9, wherein the resin comprises 10 to 95 wt % ofthe coating, based on total solids weight.
 12. The coating of claim 9,wherein the resin comprises 20 to 90 wt % of the coating, based on totalsolids weight.
 13. The coating of claim 9, wherein the coating comprisesa colorant.
 14. The coating of claim 9, wherein the coating issubstantially clear.
 15. The coating of claim 9, wherein the coating isa two component coating, and the resin is in one component and a curingagent for the resin is in another component.
 16. The coating of claim 9,wherein the epoxy resin comprises the diglycidyl ether of bisphenol A.17. The coating of claim 9, wherein the dienophile comprises acrylicacid.
 18. The coating of claim 9, wherein the dienophile comprisesmonocarboxylic acid.
 19. The coating of claim 9, wherein the coating iswater based.